The present invention relates to the field of making photography acquisitions more standard. Very often, a user has difficulties in taking high quality photography pictures of a subject which are at the same time centered, framed and perfectly focused. In addition, the greater the sophistication of the camera, the more difficult is the standardization due to the multiple options in camera settings.
Devices have been designed in order to constrain the photo acquisition for specific applications as in the case of medical photography. It has been proposed to use a rigid frame onto or within which the subject is placing a part of their anatomy such as the face. The camera is fixed on a rigid frame and tuned so that the focusing distance is corresponding to the expected position of the subject. Specifically, this approach has been used in the case of image boxes—a kind of half-spheres comprised of a fixed camera device where the subject places their head. A major drawback of such system is that it needs a physical contact between the rigid repositioning frame and the subject, which may be an issue in the case of a medical application when the subject of the photography is presenting opened wounds or burns and when there is a risk of infection. Another drawback of rigid frames is the visibility in the image which may hide some parts of the subject. Finally, such a frame can be cumbersome and quite difficult to transport.
Another way to ensure reproducibility relative to aiming distance consists in fixing a rigid spindle to the camera and to setup the focus distance so that it corresponds to the length of the spindle. Hence, by putting the tip of the spindle into contact with the subject, one can ensure a reproducible distance for picture taking. Although a spindle can be transported more easily than a rigid repositioning frame, there remains issues relative to contact with the subject and visibility of the spindle in the image, which can obstruct parts of the body.
Another way to measure the distance between a camera and a subject consists in using light beamers which are converging at the focusing distance of the camera, which can be used either to measure a distance or to automatically pilot an adaptive optics.
One example of adaptive optics making use of light beamers is presented in the German Patent EP 2 136 248 A1, SICK AG [DE], Dec. 23, 2009 (2009-12-23), in particular paragraphs [0038]-[0053] and FIGS. 1 to 3. The aim of this device is to pilot the focus of a dedicated camera in order to focus the camera at a given distance. It is not an autonomous photography accessory adapting to a standard photography camera device, and it doesn't aim at blocking the focus of its optics at a given distance but on the contrary a way to pilot the optics so that its focus distance is adapting in real time.
The international patent PCT WO 90/09560 A1, John Lysaght Limited [AU], Aug. 23, 1990 (1990-08-23), in particular page 2, line 26 and page 3, line 2, and FIG. 2 are presenting a device that aims at measuring the distances between objects by using light beamers, and more specifically to measure the relative distances between objects or parts of the same object by analyzing the relative position of light beamers on the subject. It is not a device intended to pilot focusing or to block the focus at a given distance.
The U.S. Pat. No. 6,340,114 B1, Correa Mark [US] et al, of Jan. 22, 2002 (2002-01-22) is describing a device for optical codes reading, constituted of a system to project a light pattern made of two concentric rectangles in order to make sure that the optical code to read is comprised between a minimal and a maximal distance from the reading device by making sure that the optical code is encompassed between the two projected rectangles. Notably in such as case, the device is a video camera and not a photographic camera and also the overlapping of beams is not used given that the light projector is unique. This device is one amongst many dedicated devices incorporating a light pattern projector enabling aiming at or encompassing a targeted subject. Such a device is not an autonomous photographic accessory which can adapt to a standard photographic camera, and it is also not aiming at blocking the focus distance of the optics of the camera to a given distance.
For this set of devices including light pattern projection which we just described, none is detailing any mechanism to de-activate the light beamers during picture taking. Indeed, in most of the cases, the flash light is powerful enough so that beam lights cannot be visually detected in the image. Practically speaking, it is mostly in the field of medical image analysis which is the main purpose of the present invention that it is interesting to make sure not to bias the image by stray light such as those created by the light beamers. Indeed, medical image processing algorithms are generally sensitive enough to perceive relatively reduced stray light and in this field of application, any source of bias in measurement must be avoided.
The devices using light pattern projection as just described are concerning video cameras or photographic cameras dedicated to industrial measurements for which extinguishing light beamers during the image acquisition is not important enough to justify the design of a specific extinguishing mechanism.
These devices are not adaptable to existing standard photographic cameras but are integrated systems specifically designed for their industrial application objectives. These integrated devices are therefore not a photographic equipment accessory. Their function is not to block the focus distance of a standard photographic camera in combination with light pointers in order to make is useful for standardized photography taking.